SINGAPORE, Feb. 23 -- Investors should remain long on copper as the metal may rise to $8,500 a metric ton, a level not seen since July 2008, Standard Chartered Bank said, citing trading patterns.

Gains are expected to the next resistance at $7,530 a ton, London-based Dan Smith, the bank's metals analyst, wrote in a note yesterday. This should "serve as the pivot" for $8,500 further out, Smith wrote. A "long" is a bet on higher prices and so-called resistance levels may identify clusters of sell orders.

Copper for delivery in three months on the London Metal Exchange, which more than doubled last year in part because of stockpiling in China, has fallen 1.2 percent this year. The metal, used in construction and automobiles, reached a record $8,940 a ton on July 2, 2008, and traded 1 percent lower at $7,259.75 by 10:17 a.m. Singapore time.

Base metals are expected to continue to rally and Smith also recommended looking for "further strength" in nickel and zinc.

"Nickel prices turned above the $18,900 trendline resistance, with $21,325 and $21,525 marking the next area to watch," Smith wrote. The metal reached a one-year high of $21,325 on Aug. 13, 2009 and a more than one-month peak of $21,525 on Aug. 21, 2008. "Zinc prices are starting to push above the 60-day moving average, which is bullish."

In technical analysis, investors and analysts study charts of trading patterns and prices to forecast changes in a security, commodity, currency or index.